I'm not so sure about Chihiro, though Keima does have a point. However, even during her arc, Chihiro was pretty mean to Keima. That's just the kind of girl she is. To me, it's pretty ambiguous at this point. Ayumi though, definite.

Chihiro has had bonus appearances because she's Elsee's close friend. Her "new" behavior isn't completely out of character. She's pretty astute in her own right. There's the possibility she's being meaner than normal to Keima because she has a suspicion about how much Ayumi likes him. What girl wouldn't want to defend one of her best friends?

I smirked at Elsee dancing on television with dizzy eyes, and Haqua's line about calling him trash repeatedly for being a two-timer.